As other's have already mentioned, Symbian traces it routes back to the early Psion Organisers, which ran a pre-emptive multitasking operating system before Windows did, and was thought to be Microsoft's biggest competitor back then [1]. I've used the Psion II, and had a 3a, which you could program in their basic-like OPL language. The 5mx looked like Win95 in a palmtop and was a great pocket computing device with a reasonable keyboard, terminal, email client and internet connectivity. I remember back in 1998 or so looking longingly at the expensive phones that came with a built-in modem (Nokia 6210 and Ericsson R320 from memory), so I could use email and web on the go. Nokia took EPOC and became the lead in the Symbian consortium, using it on spiritual successors of the Psions - the 9300 and 9500, and when the E90 came out with a magnesium case and built in keyboard I had to get one.

That was in 2007, around the time of the first iphone, but was so much more capable. Incredible at that time having all that power in your pocket. I never got lost in foreign cities because I could just get a GPS lock on the train station and find my way back, without using very expensive data in a foreign country. It was a strange thing being able to access the internet anywhere back then. In some ways it was a better time - social media networks hadn't cottoned on to the ability to deliver dopamine from the pockets of world's population, so the device felt powerful, but not like a ball and chain, or distraction-device like my pixel does these days.

[1] https://www.independent.co.uk/news/why-is-bill-gates-so-scar...